One of the participants in the study, who was a long-term alcoholic, had imbibed more than four drinks. she then narrated an incident to one of her newly made acquaintances, who realizes that the incident could not possibly have occurred. the inebriated participant is most probably suffering from:

Korsakoff's syndrome.

Explanation:

Korsakoff's syndrome may be defined as a type of amnestic disorder and caused by the deficiency of thiamine. The prolonged ingestion of alcohol is the main cause of this Korsakoff's syndrome.

A participant was long-term alcoholic and has distorted memory. These all are the symptoms of Korsakoff's syndrome. The participant is most probably suffering from the Korsakoff's syndrome.

Thus, the answer is Korsakoff's syndrome.